Although the quantum nature of light has been discovered over a century ago, controlling its quantum states still presents a considerable technical challenge. The past fifteen years have shown significant progress in solving it. Using entangled light sources, linear optical transformations and conditional measurements, we are able to produce and measure increasingly complex quantum optical states. I will review some of the new states of light that have been studied in the past years, methods of their preparation and measurement. I will concentrate on the single-photon Fock state, the displaced Fock state, and the dual-rail optical qubit. Then I will show how combining these approaches lead us to a surprising new result: a micro-macro entangled optical state (Schrödinger cat) with the macroscopic part containing over a hundred million photons.